Safety lifting device



Nov. 18, 1958 H. v. STODDARD ET AL 2,850,729

SAFETY LIFTING DEVICE Filed Jan. 12, 1956 5 Sheets-Sheet 2 NOV' 18, 1958 H. v. s'roDDARD ET Ax. 2,860,729

SAFETY LIFTING DEVICE Filed Jan. l2, 1956 3 Sheets-Sheer, 3

7W 5MM/7W United States Patent O SAFETY LrFriNG DEVICE Howard Vincent Stoddard, Nutley, David Monroe Baeder, Packanack Lake, and Sidney Messori, West Orange, N. I., assignors to Essex Conveyors, Inc., Newark, N. J., a corporation of New Jersey Application January 12, 1956, Serial No. 558,661`

2 Claims. (Cl. IS7- 66) This invention relates to a novel lifting device and, more particularly, it relates to a lifting device which is suitable for transporting material between adjacent floors in a building.

In conventional lifting devices which are used for transporting material between adjacent floors in a building, the structures are often cumbersome and occupy more space than is desired, or they are readily subject to mechanical failure. In one type of lifting device, the platform upon which the material is supported is fastened directly onto the power lift such as a hydraulic ram. This lifting device has the obvious disadvantage of requiring an excessive amount of space for the reason that the hydraulic ram is positioned below the lifting platform in a floor area which is not part of the places between which delivery takes place. Therefore, unless suboor space is available for the hydraulic ram, this type of device cannot be used for floor-to-floor delivery.

Another type of device which is used for transporting material between adjacent floors in a building involves the use of counterweights. Usually, the counterweights are located in areas outside of the floors involved in the delivery, consequently such a device is not satisfactory where only the areas involved in the places of delivery are available. ln some devices the counterweights serve to lift the platform by direct attachment of a lifting cable to arms or cradles which are fastened to the lifting platform. Such devices have the disadvantages of (l) the lift members occupying more space than is desired, and (2) there is the possibility that the lifting cable might get caught or jammed with serious results. Further, such -a device lacks safety means for protecting against cable Jfailure. It is apparent from the foregoing remarks that there is a great need at present for a lifting device which occupies minimum space and is mechanically safe and usable for long periods of time. need for a lifting device which contains means for preventing damage in case of lifting power failure. It is the purpose of this invention to provide a lifting device which is unusually well adapted for transporting materials between floors in a building or an enclosure.

An object of this invention is to provide a novel lifting device.

Another object of this invention is to provide a novel lifting device which is adapted for conveyance of material between adjacent levels or floors in a building or enclosure.

Still another object of this invention is to provide a novel lifting device which is effective for floor-to-oor transport of material and which is safe, compact and mechanically efcient for the purpose.

Other objects and advantages of this invention will become apparent from the following description and explanation thereof.

Generally, the lifting device of the present invention comprises a stationary frame containing two spaced vertical travelways or slides, an intermediate frame disposed between the travelways of the stationary frame and oper- In addition, there is 2,860,729 Patented Nov. 18, 1958 rlice atively associated therewith for vertical movement, the intermediate frame containing two spaced vertical travelways or slides, a lifting frame positioned between the travelways of said intermediate frame and operatively associated therewith for vertical movement, a lifting platform laterally attached to the lifting frame and adapted to support weight thereon, power means associated with the intermediate frame to provide vertical movement ofv the same, means for interconnecting the intermediate frame and lifting frame whereby the latter is moved vertically, and the aforesaid frames being in planar alignment.

In order to provide a full understanding of this invention reference will be had to the accompanying drawings which form a part of this specification and wherein:

Fig. l is a front elevation of a lifting device of this invention;

Fig. 2 is a view taken along the line 2-2 of Fig.

Pig. 3 is a view taken along the line 3-3 of Fig.

Fig. 4 is a view taken along the line 4 4 of Fig.

Fig. 5 is a view taken along the line 5--5 of Fig;

Fig. 6 is an isometric view of the lifting device;

Fig. 7 is an alternative specific embodiment for raising the cover of the oor above; and

, Fig. 8 is a view of the power means including the fluid system.

in the drawings, particularly Fig. 2, vertical stationary frame 11 consists of two sections, each comprising a channel beam 12 having welded to the web thereof an angle iron 13. The combination of channel beam 12 and angle iron 13 forms two longitudinal channels, the channel or beam 12 providing a travelway or slide for guiding a movable frame, and the channel between the angle iron 13 and the flange of channel beam l2 providing clearance for passage of the movable frame. Stationary frame 11 has horizontal braces 14 welded to the flanges of the angle irons 13 at spaced points along the lengths thereof for supporting and positioning the two travelways spaced from each other. Thus, the channel beam and angle iron combination provides the vertical support members of the device as Well as travelways or slides for the purpose of this invention. Near the top of the stationary frame 11 a horizontal angle iron 15 is welded to the anges of angle irons 13 for the dual purpose of providing rigidity to the channel beam-angle iron units and a place for securing the ends of link chains 16. At the bottom end of each of the channel beams 12 there is welded a transverse horizontal platform support consisting of an angle iron 17. The platform supports 17 have welded to the top edges thereof the platform or plate 18. The platform 18 serves to support and carry loads between the floors in a building. In addition, horizontal plate 18 has integrally formed therewith an upwardly extending side 19 which is adjacent to the stationary frame but spaced therefrom suiciently to avoid interference. The vertical section 19 serves the purpose of preventing supported loads from shifting into the lifting device as the platform is moving.

An intermediate frame 20 consisting of two vertical channel beams 21 is disposed between channel beams 12. The channel beams of the intermediate frame 20 are maintained horizontally apart with the grooves or channels facing each other by means of horizontal braces 22 affixed at spaced points along the lengths thereof. The braces 22 are welded to plates 23 which in turn are welded directly to the flanges of channel beams 21. In this way, lifting frame 24 which moves vertically between channel beams 21 is odset from and cannot contact braces 22. Further, plates 23 extend laterally in the direction of channel beams 12 to an overlapping position therewith and thus they also serve as guides to prevent intermediate frame 20 from rocking or fallingout of position. On each lower section of channel beams 21 there is welded a plate or guide 25 on the side away from the braces 22. These guides eX- tend horizontally in the. direction of channels 12 of the stationary frame to, an overlapping position therewith. Below guides 25 there is welded a plate or guide 26 on the side of each channel beam 12 of the stationary frame 11 away from braces 22. These guides extend horizontally in the direction of channel beams 21 to an overlapping position therewith. Therefore, the combination of guides 25 and 26 andplates 23 serve to minimize lateral movement of intermediate frame from its inside position relative to stationary frame 11. An additional purpose of guide will be discussed hereinbelow. A pair of flanged wheels or rollers 27 are rotatably mounted on the lower half of each channel beam 21 at the side facing the longitudinal groove of channel beam 12. The wheels fit within the longitudinal groove of each channel beam 12 for vertical movement therein. A safety feature of the present example is that failure of all wheels does not result in the intermediate frame 20 falling out of position between the channel beams 12 of the stationary frame because guides 25 and 26 serve to keep the frames in a vertical position.

There is welded to upper end of each channel beam 21 a horizontal I-beam 28. A hydraulic ram or lift 29 containing a cylinder 30 and a vertically movable piston 31 is disposed centrally within the intermediate frame 20. The end of piston 31 is affixed to beam 28 and thereby the intermediate frame may be raised or lowered to any desired level within the design limits of the lift device. On the inner side and at the upper end of each channel beam 20, just below the position of `beam 28, there is rotatably mounted a sprocket 32. Each sprocket has mounted thereon a link chain 16. The lower ends of the link chains 16 are fastened to the top ofthe channel beam 33 of the lift frame 24. The other end of each chain 16 is fastened to angle iron 15 of the stationary frame. The position of the plane of movement of each link chain 16 is adjacent to channel beams 21 in order to obtain superior performance. By placing the link chains as far from the hydraulic ram as possible in the directiony of the channel beams 21, any lateral movement due to eccentric loadingjof the platform 18 is minimized. Stated another way, the extreme positions of link chains 16 serve notably to reduce rocking or lateral movement of lifting frame 24. Further, by having the link chains in substantially vertical positions, any force having a horizontal component resulting from the pull on the link chains is kept small. This in turn reduces the tendency for the lifting frame to be pulled out of` position relative to the intermediate frame. Therefore,pit is apparent that me smaller the horizontal component of force, the less the tendency of the lifting frame to rock in its.vertical positionwithinfthe intermediate frame. The channel beams 33 ofthe lifting framey are maintained in. vertical positions with the groovesor channels facing each other by means of horizontalV channels 34, which are welded thereto at the upper and lower ends thereof. Further, there is rotatably mounted on the side of each channel beam 33 facing the groove of channel beam 21, a pair of spaced flanged wheels or rollers` 35 having the same construction as flanged wheels 27. Flanged wheels 35 fit into the grooves of channel beams 21 and thereby provide for vertical movement of lift frame 35. In addition, as shown in Fig. 5, there is welded on the side of each. channel beam 33, on the same side as flanged wheels 35, a channel beam section or internal guide 36. Guide 36 is a smaller sized channel beam which tswithin the groove of channelbeam 21. In addition to the support provided by means of horizontal channels 34, the lift frame contains additional support or bracing by means of diagonal braces 37. Each brace 37 has one end welded to channel beam 35 and. the other end to cross-bar 34. Thediagonal braces 37 are positioned so as not to interfere with hydraulic ram 29.

The upward vertical movement of intermediate frame 20 is stopped at a predetermined height. As shown in Fig. 4, an adjustable stop 38 is fastened by means of bolts 39 to the side of channel beam 12 at the upper part thereof to accomplish this purpose. The adjustable stop 38 consists of a channel'section 40 having a longitudinal slot 41 and a horizontal lug 42. In operation, the horizontal guides 25 contact lugs 42 at the uppermost position of intermediate frame 20, causing the pump 59 associated with the hydraulic lift 29 to cease operating, as explained hereinbelow. The guides 25 serve several purposes in the operation of the lifting device of this invention, in addition to the foregoing. The guides also serve to prevent rocking or lateral movement of the intermediate frame relative to the stationary frame, and they maintain the intermediate frame in a vertical position should the iianged wheels 27 fail.

The flanged wheels 27 guide the vertical movement of intermediate frame 20 within the grooves of channel beams 12. The flanged parts of the wheels keep channel beams 21 of the intermediate frame from contacting channel beams 12. Since these flanged wheels may wear after prolonged use or they may fail, additional guides 44 are provided for this purpose. These guides are horizontal bars and one of each is welded to the side of each channel beam 21 above the position of the uppermost flanged wheel 27, thereby maintaining beams. 12 and 20 spaced from each other.

As shown in Fig. 6, there is welded to the top of each beam 33 and the horizontal channel 34, a vertical connector 45. These connectors 45 serve to hold in position the floor cover lift 46. The floor lift 46 consists of two vertical members 47 with a rectangular shaped frame 48 supported on the upper ends thereof. On the upper side of each corner of the frame 48 there is disposed a short vertical lug or male portion 49. These male portions engage grooves 50 which depends from each end of two parallel plates 51. The horizontal plates 51 are fastened to the underside of a floor cover 52. In operation, the floor cover lift 46 moves upwardly with lift frame 24 and at the height of the floor cover 52, lugs 49 engage with grooves 50 and the floor cover is lifted from position and carried on frame 48, thus providing an opening for passage of the lifting platform 18. An alternative method of raising floor cover 52 is shown in Fig. 7. In this embodiment floor cover 52 is hinged to the building structure 53 by means of two hinges 54. The floor cover lift consists of two spaced parallel arms 55 which are adapted to engage with connectors 45. At the upper end of each arm 55 is fastened rigidly a laterally disposed arm 56. A roller bearing 57 is rotatably mounted `on the unattached end of each lateral arm 56, and a roller bearing 58 is mounted on each juncture of vertical arm 55 and lateral arm 56. The lateral arm is inclined from the juncture to provide less vertical loading thereon. In .operation, as the floor cover lift rises, Ibearings 57 engage floor cover 52 causing floor cover 64 to open by pivoting on hinges 54. As the floor cover continues to rise, bearings 58 assume support of the oor cover 52 until the same is in a substantially vertical position.

The power means of this invention includes a gear pump 59 which is driven by electric motor 43.` The discharge end of gear pump 59 is connected to the hydraulic cylinder 29 by means of a single flexible line 60. `The hydraulic fluid is stored in tank 61 from which gear pump 59 draws its supply. The discharge line of gear pump 59 contains a one-way check Valve 65 which maintains pressure in the hydraulic cylinder if the pump stops operating. T he discharge line of gear pump 59 also contains a return line 66 to tank 61. Positioned downstream of the one-way check `valve in the discharge line isY a solenoid operated two-way valve 67 interconnecting` hydraulic cylinder 29 and the gear pump in a normally open position and interconnecting with the return' line in a Anormally closed position. t l

To `operate .the device,.electric motor 43 lis started by pressing one of two spring loaded push buttons of a suitable starting switch 68, which buttons are marked for up or down movement of the lift platform 18. The switch Ais located away from the lift device itself.` The push buttons are in a normally open-circuit position, and it is necessary to keep either button depressed continuously in order to close the circuit which operates the motor 43. Thus it is impossible for the operator -to be on the lift while operating it or to leave the control switch while the lift is moving. In this way, should a mishap occur, the operator is on hand to take any action which is necessary under the prevailing circumstances.

Assuming that platform 18 is in its lowest position, the operator presses the up button of the starting switch thus causing the electric motor 43 to operate pump 59, which in turn forces hydraulic tiuid to ow from tank 61, through discharge line 60 and thence into hydraulic cylinder 29. The pressure developed in hydraulic cylinder 29 causes the piston 31 to rise, and thereby the intermediate frame is elevated the same distance. Since the intermediate frame is operatively associated with lift frame 24 by means of link chains 16 and sprockets 32, for every unit of distance that the intermediate frame moves vertically, the lift frame moves two units. Thus it is not necessary to sink the hydraulic cylinder in the oor in order to permit the piston to attain its fully retracted position.

Platform 18 can be raised and held at any elevated position within its operating travel by merely releasing manual pressure against the up button of the starting switch. Such action stops motor 43. Since the discharge line Ibetween pump 59 and the hydraulic cylinder 29 contains a one-way check valve, the pressure in the cylinder is confined, thus maintaining the lift platform in the position it reached at the time the push button was released.

As platform 18 rises, the floor lift 46 rises in correspondence therewith until lugs 49 engage grooves 51 of the elevated floor. Once lugs 49 are engaged with grooves 51, the iioor cover is lifted from its position and carried upwardly in a supported position on the oor lift 46. In the uppermost position of the lift device, lift platform 18 is in alignment with the upper floor. At about the same time, guide 25 is arranged to engage stop member 42 of the stationary frame. Normally it is expected that the operator will stop the operation of the device at this point, however, should the operator fail to act, the `back pressure developed by guide member 25 and stop 42 engaging, will actuate an internal release or pop valve (not shown) in pump 59, thus causing the pumped fluid to circulate to the suction `side of the pump. In this way, the pressure in the hydraulic -cylinder cannot increase beyond the pressure at which the internal valve in the pump will release or become actuated.

When it is desired to lower platform 18, the down button of the starting switch is pressed. Pressing the down button energizes the solenoid of the two-way valve and switches the valve position to permit fluid to liow from the hydraulic cylinder 29 to tank 61. At the lowest position of platform 18, the pressure in the hydraulic cylinder 29 and the pressure in tank 61 are equal. The valve orifice of the two-way valve is such that the rate of ow of hydraulic fluid back through the two-way valve into the tank is slow enough to permit platform 18 to descend gradually.

While the above method of operating the lift device is preferred, it should be understood that various modifications and alternatives can be used without departing from the scope of this invention. For example, the back pressure developed by guide 25 engaging stop 42 can cause motor 43 to overload, and at a predetermined overload or current, a circuit breaker will open the circuit of the motor, thus stopping pumping operations. Alternatively, the discharge line of pump S9 can contain a Mercoid type switch, which is constructed with a Bourdon tube to move or trip a mercury switch at a predetermined pressure, thus opening the circuit of the motor 43.

In addition, if desired, the intermediate frame 20 can be associated. with an additional frame by means of sprockets and link chains, as in the above example, and n the second frame can be associated with the lift frame 24 by means of another set of sprockets and link chains. This cascading of frames can be multiplied to any reasonable extent for securing additional lifting height as required.

What is claimed is: n

l. An apparatus comprising a stationary frame containing two spaced vertical channel beams having the grooves thereof facing each other to provide travelways, at least one of said channel beams containing an adjustable stop member attached to the upper end thereof, a movable intermediate frame disposed between the channel beams of the stationary frame, said intermediate frame containing two spaced vertical channel beams having the grooves thereof facing each other to provide travelways, each of said channel beams of the intermediate frame containing on each side thereof at least one guide member projecting laterally in direction of the stationary frame and being so constructed and arranged that each channel beam of the stationary frame is positioned between at least two guide members, a pair of rotatable flanged wheels mounted on the side of each channel beam of the intermediate frame facing the groove of a channel beam of the stationary frame for engagement therewith, a lifting frame disposed between the channel beams of the intermediate frame, said lifting frame containing two spaced vertical channel beams having the grooves thereof facing each other, a pair of rotatable tianged wheels mounted on the side of each channel beam of the lifting frame facing the groove of the channel beam of the intermediate frame for engagement therewith, each of the channel beams of the lifting frame containing a guide member on the side thereof facing the groove of the intermediate frame and being so constructed and. arranged that the guide member engages the groove of the intermediate frame, said intermediate frame containing a horizontal member fastened to the upper ends of the vertical channel beams, a hydraulic lift containing a cylinder disposed between the channel beams of the intermediate frame, said hydraulic lift containing a vertically movable piston having the end thereof fastened to the horizontal member of the intermediate frame, a sprocket wheel being rotatably mounted at the top on the grooved side of each channel beam of the intermediate frame, a link chain mounted on each sprocket and having one end fastened to the stationary frame at a level below the position of the sprocket and the other end fastened to the top of the lifting frame, the plane of movement of the link chain being closely positioned to each channel beam of the intermediate frame, a oor cover lifting frame being disposed on said lifting frame, said oor lifting frame having a vertical member attached to the upper part of each channel beam of said lifting frame and floor engaging members laterally disposed on the upper part of said vertical members, the floor cover lifting member being adapted to move an elevated floor cover for passage of the lifting platform through the resulting opening, and the aforesaid frames being in planar alignment.

2. The apparatus of claim l being further characterized lby the additional presence of a pumping means associated with the hydraulic cylinder for the supply of hydraulic fluid thereto, relief means responsive to pressure actuation and adapted to prevent the pressure developed by said pumping means to exceed a predetermined value, and said guide member and stop member being so arranged and constructed that the same engage at the uppermost position-of saidfintermgdiate jfrrne,A andlbusl-cause said;; relief means n'LQ be actuated ,1:

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